Piezoelectric vibration angular velocity sensor

Abstract

An angular velocity sensor includes a protrusion protruding in a Y′-axis direction and extending in an X-axis direction on a main surface of a rotated Y cut quartz plate, and an excitation electrode and a detection electrode formed on the main surface adjacent to this protrusion. This excitation electrode excites thickness-shear vibration in the X-axis direction on the quartz substrate, exiting vibration on the protrusion. Then, the protrusion is bent and displaced due to Coriolis force acting in a direction orthogonal to the vibration of the protrusion corresponding to a rotation around an Y′ axis. This displacement at the protrusion is applied to the quartz substrate as stress. The detection electrode detects change of this stress, thereby angular speed added to the angular velocity sensor is detected.

1. An angular velocity sensor, comprising:
 a quartz substrate in a flat plate shape being cut out from quartz single crystal rotated by a range of zero to one hundred eighty degrees around an X-axis from a crystal coordinate system (X, Y, Z) to a coordinate system (X, Y′, Z′) so that a main surface is parallel with respect to the X-axis and a Z′-axis of the coordinate system (X, Y′, Z′); 
 a protrusion monolithically formed with the quartz substrate on the main surface so as to protrude in a Y′-axis direction and extend in an X-axis direction; 
 an excitation electrode and a detection electrode formed adjacent to the protrusion on the main surface, wherein vibration is excited at the protrusion by exciting thickness-shear vibration in the X-axis direction on a portion having the excitation electrode and the detection electrode formed on the quartz substrate by an electric field applied to the excitation electrode, and the protrusion is bent by Coriolis force acting corresponding to a rotation around a Y′-axis, and displacement thereof is transmitted to the quartz substrate, so that the detection electrode detects change of stress applied to the quartz substrate. 
 
     
     
       2. The angular velocity sensor according to  claim 1 , wherein the quartz substrate is an AT cut quartz substrate. 
     
     
       3. The angular velocity sensor according to  claim 2 , wherein the protrusion is formed between the excitation electrode and the detection electrode in a plain view of the main surface. 
     
     
       4. The angular velocity sensor according to  claim 3 , wherein the protrusion is formed in a plurality of numbers in the X-axis direction. 
     
     
       5. The angular velocity sensor according to  claim 4 , wherein each of the plurality of protrusions is different in size. 
     
     
       6. The angular velocity sensor according to  claim 3 , wherein the protrusion is formed in a plurality of numbers in a Z′-axis direction. 
     
     
       7. An angular velocity sensor, comprising:
 a quartz substrate in a flat plate shape being cut out from quartz single crystal rotated by a range of zero to one hundred eighty degrees around an X-axis from a crystal coordinate system (X, Y, Z) to a coordinate system (X, Y′, Z′), so that main surfaces are parallel with respect to the X-axis and a Z′-axis of the coordinate system (X, Y′, Z′); 
 protrusions monolithically formed with the quartz substrate on both of the main surfaces so as to protrude in a Y′-axis direction and extend in an X-axis direction; 
 an excitation electrode and a detection electrode formed adjacent to the protrusions on the main surfaces, wherein vibration is excited at the protrusions by exciting thickness-shear vibration in the X-axis direction on a portion having the excitation electrode and the detection electrode formed on the quartz substrate by an electric field applied to the excitation electrode, and the protrusions are bent by Coriolis force acting corresponding to a rotation around a Y′-axis and displacement thereof is transmitted to the quartz substrate, so that the detection electrode detects change of stress applied to the quartz substrate. 
 
     
     
       8. The angular velocity sensor according to  claim 7 , wherein the quartz substrate is an AT cut quartz substrate. 
     
     
       9. The angular velocity sensor according to  claim 8 , wherein the protrusions are formed between the excitation electrode and the detection electrode in a plain view of the main surfaces. 
     
     
       10. The angular velocity sensor according to  claim 9 , wherein the protrusions are formed in a plurality of numbers in the X-axis direction. 
     
     
       11. The angular velocity sensor according to  claim 10 , wherein each of the plurality of protrusions is different in size. 
     
     
       12. The angular velocity sensor according to  claim 9 , wherein the protrusions are formed in a plurality of numbers in a Z′-axis direction.